Chanunthorn Chananonnawathorn

Tuberculosis determination using SERS and chemometric methods

Nanostructures have been multiplying the advantages of Raman spectroscopy and further amplify the advantages of Raman spectroscopy is a continuous effort focused on the appropriate design of nanostructures. Herein, we designed different shapes of plasmonic nanostructures such as Vertical, Zig Zag, Slant nanorods and Spherical nanoparticles employing the DC magnetron sputtering system as SERS-active substrates for ultrasensitive detection of target molecules. The fabricated plasmonic nanostructures sensitivity and uniformity were exploited by reference dye analyte. These nanostructures were utilized in the label free detection of infectious disease, Tuberculosis (TB). For the first time, TB detection from serum samples using SERS has been demonstrated. Various multivariate statistical methods such as principal component analysis, support vector machine, decision tree and random forest were developed and tested their ability to discriminate the healthy and active TB samples. The results demonstrate the performance of the SERS spectra, chemometric methods and potential of the method in clinical diagnosis.

Crucial role of reactive pulse-gas on a sputtered Zn3N2 thin film formation

Herein, we demonstrate a powerful technique, known as reactive gas-timing (RGT) rf magnetron sputtering, to fabricate high quality Zn3N2 thin films at room temperature without applying any additional energy sources. A single phase of Zn3N2 film formation can only be obtained when a reactive pulse-gas of N2 is utilized. We find that selecting a small atomic mass of sputtered reactive gas coupled with the pulse-gas technique is very crucial to adjust the number of sputtered atoms obtained from the target and enrich the forming energy of the sputtered Zn3N2 films during the deposition process. Our results highlight that the RGT technique is a promising method to fabricate high quality sputtered compound thin films that can be applied in flexible devices. A simplified model of the materials system at the surface region of the de-nitride Zn3N2 during ion bombardment is also presented.

Effect of Oxygen Flow Rate and Post Annealing on Vanadium Oxide Thin Films Prepared by DC Pulse Magnetron Sputtering

In this work, we investigated V2O5 thin films prepared by a DC pulse reactive magnetron sputtering at ambient conditions. The effects of oxygen flow rates during the film deposition and post annealing in air atmosphere were explored. The V2O5 thin films were sputtered from vanadium target onto silicon wafer and glass slide substrates at room temperature. The as-deposited V2O5 thin films were annealed at 200°C under air atmosphere. The films were then examined for their crystallinity, physical microstructures, and optical transmission. The crystallinity and morphology of the films were investigated by grazing incident x-ray diffraction, atomic force microscopy, and field-emission scanning electron microscopy. The optical transmission was determined by UV-Vis Spectrophotometer. The results showed that the as-deposited films were amorphous, whereas the post annealed films indicated V2O5 phase in all samples. The increase in the oxygen flow rates during the deposition led to the decrease in the deposition rate, film thickness, and film surface roughness. In addition, the oxygen flow can increase the average transmission of the V2O5 thin films. The effects of the annealing treatment of the optical transmission spectra will be discussed.

Effects of Precursor Concentration on Hexagonal Structures of ZnO Nanorods Grown by Aqueous Solution Method

The ZnO nanorods were fabricated on top of the seeded gold layer by the aqueous solution method with the solution of zinc nitrate and hexamethylenetetramine (HTMA) at 90°C for 24 hours. The variety of the ZnO nanorods were prepared and investigated based on the precursor concentrations, in a range of 1 to 40 mM. The physical morphologies and crystal structures were characterized by field-emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD), respectively. The results showed that, with the small precursor concentrations, the lateral growth of the nanorods was highly significant when compared to their axial growth. The precursor concentration of 20 mM was best optimized for the preparation of the ZnO nanorod arrays with the hexagonal structures at the highest rod diameter and length. At the higher concentrations, although the nanorod size remained nearly constant, the length was however rapidly decreased. Further analyses also proved that, with the increased precursor concentrations, the number density of the ZnO nanorods was progressively increased along with the more complete hexagonal wurtzite structures.

Controllable decoration of Au NPs on zinc oxide nanorods template by magnetron sputtering technique for reusable-SERS active surface enhancement

Surface Enhanced Raman Scattering (SERS) is a new invention developed to expand the Raman signal. The SERS chip has a performance to enhance the Raman signal up to a million times. Nevertheless, the chip has some disadvantages which are high cost and it is disposable device. In this research, the controllable decoration of gold nanoparticles on zinc oxide nanorods template for a reusable SERS chip is investigated. Time periods to decorate gold particles are controlled by using DC magnetron sputtering technique from 15 to 450 s. The zinc oxide nanostructures are grown by hydrothermal. The physical structures of the reusable SERS chip are analyzed by Field Emission Scanning Electron Microscope (FE-SEM). The sizes and thicknesses of the gold particles attached to the ZnO nanorods are measured from FE-SEM images. The efficiency to amplify Raman signal of the reusable SERS chip is tested by dropping methylene blue (MB). UV light is used to activate self-cleaning property of the reusable SERS chip. From the results, sputtering gold nanoparticles for 270 s shows the highest performance to amplify Raman signal of methylene blue, up to 1 × 10−6 M, however; it takes 450 minutes of UV cleaning before reuse again. On the other hand, sputtering gold nanoparticles for 15 s shows the fastest clean surface after UV cleaning, though the chip can amplify the Raman signal up to 1×10−5 M.Surface Enhanced Raman Scattering (SERS) is a new invention developed to expand the Raman signal. The SERS chip has a performance to enhance the Raman signal up to a million times. Nevertheless, the chip has some disadvantages which are high cost and it is disposable device. In this research, the controllable decoration of gold nanoparticles on zinc oxide nanorods template for a reusable SERS chip is investigated. Time periods to decorate gold particles are controlled by using DC magnetron sputtering technique from 15 to 450 s. The zinc oxide nanostructures are grown by hydrothermal. The physical structures of the reusable SERS chip are analyzed by Field Emission Scanning Electron Microscope (FE-SEM). The sizes and thicknesses of the gold particles attached to the ZnO nanorods are measured from FE-SEM images. The efficiency to amplify Raman signal of the reusable SERS chip is tested by dropping methylene blue (MB). UV light is used to activate self-cleaning property of the reusable SERS chip. From the res...

Omnidirectional antireflection and electrochromic properties of WO3 nanorods prepared by oblique angle deposition

In this study, the electrochromic tungsten oxide (WO3) nanorods were successfully prepared by reactive dc magnetron sputtering with oblique angle deposition (OAD) technique on silicon (100) wafer, glass slide and ITO coated glass substrates. The influence of sputtering power on the WO3 nanorods were investigated by grazing incident X-ray diffractometer, field emission scanning electron microscope and spectrophotometer. The thickness of the WO3 nanorods layer was controlled at 400 nm by adjusting the deposition time in order to optimize the electrochromic property. These WO3 nanorods had an amorphous and high transmittance with omnidirectional antireflection property. In addition, the prepared electrochromic WO3 nanorods sample were also shown high optical contrast which demonstrated considerable potential in the smart window application.In this study, the electrochromic tungsten oxide (WO3) nanorods were successfully prepared by reactive dc magnetron sputtering with oblique angle deposition (OAD) technique on silicon (100) wafer, glass slide and ITO coated glass substrates. The influence of sputtering power on the WO3 nanorods were investigated by grazing incident X-ray diffractometer, field emission scanning electron microscope and spectrophotometer. The thickness of the WO3 nanorods layer was controlled at 400 nm by adjusting the deposition time in order to optimize the electrochromic property. These WO3 nanorods had an amorphous and high transmittance with omnidirectional antireflection property. In addition, the prepared electrochromic WO3 nanorods sample were also shown high optical contrast which demonstrated considerable potential in the smart window application.

Hydrothermal Growth of ZnO Nanorods along the Ultra-Thin ZnO Seed Layer Prepared by Magnetron Sputtering

ZnO nanorods were grown on magnetron sputtered ultra-thin ZnO seed layers through a hydrothermal method. Before ZnO nanorods growth, the ultra-thin ZnO seed layer has been annealed at temperatures ranging from 100 to 400°C in air. The influence of annealing treatment on the crystalline structure of the ultra-thin ZnO seed layers has been investigated by X-ray diffraction (XRD). The size and density of final prepared ZnO nanorods were investigated by field-emission scanning electron microscopy (FE-SEM). It was found that the length and the aspect ratio of the ZnOnanorods can be readily tuned by control of the ZnO ultra-thin seeds layer which results from the annealing treatment process.

Effect of Annealing Temperature on Electrochromic Properties of Tantalum Oxide Thin Films Deposited by DC Reactive Magnetron

The effect of annealing temperature on the electrochromic properties of the tantalum oxide (TaO) thin films deposited on silicon wafer (100) and indium tin oxide (ITO) substrates by dc reactive magnetron sputtering was investigated. The films were annealed at 300, 400 and 500 °C in vacuum for 2 hour. The crystalline structure, morphology, optical properties and electrochromic properties of as-deposited and annealed film were deduced by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), spectroscopic ellipsometry and ultraviolet–visible (UV–vis) spectrophotometery, respectively. The reflective index of TaO thin films increased with increasing annealing temperature. The result indicated that the annealed TaO thin film showed better performance than the as-deposited film.

Fabrication and Characterization of Antibacterial Tantalum Oxide Thin Films Deposited by Reactive Magnetron Sputtering

Tantalum oxide (TaO) thin films were deposited by dc reactive magnetron sputtering at room temperature. A target of tantalum (99.995%) and a mixture of argon and oxygen gases were used to deposit TaO films on to silicon wafers (100) and BK7 glass substrate. The effects of annealing temperature (300–700 °C) on structural, morphology and anti-bacterial properties were investigated. Grazing incident X-ray diffraction (GIXRD), atomic force microscope (AFM) measurements are carried out to identify the crystalline structure, film morphology and surface roughness, respectively. The antibacterial behavior of the tantalum oxide thin films will be discussed in this paper.

Growth of Nanostructure Silver Films by DC Magnetron Sputtering for Surface Enhanced Raman Scattering Substrate

Nanostructure silver films were obtained by dc magnetron sputtering at room temperature. The influences of deposition time on the morphology and optical properties were studied by field-emission scanning electron microscope and UV-vis NIR spectrophotometer. It was found that the optical properties of the nanostructure silver film can be effect by surface morphology. The surface enhanced Raman scattering activities of nanostructure Ag films were demonstrated by methylene blue (MB) as probing molecules while the detection limit of MB was found to be as low as 10-5 M from this SERS substrate.